Stable isotope tracers have become invaluable tools with which to investigate human metabolism. This laboratory has been involved in the application and development of stable isotope tracer methods for the past 20 years. New kinetic models and analytical approaches have been developed in this lab to investigate various aspects of glucose, fat and protein metabolism. The specific goal of this core laboratory is to make available mass spectrometry analysis for all projects involved with the Pepper Center. In a more general sense, we will assist investigators in all aspects of tracer methodology necessary to use this approach to study metabolism in elderly individuals. We have all the equipment necessary to perform stable isotope enrichment measurement, including five quadruple gas chromatograph mass spectrometers, a gas chromatography- combustion-isotope ratio mass spectrometer interfaced to an elemental analyzer. We also have expertise in experimental design, performance and analysis of tracer studies, and in mathematical modeling. Finally, we are actively involved in training in education. Every year we offer an intensive, one-week formal course on tracer methodology that is open to interested investigators. We also have a Ph.D. program on human metabolism/nutrition, and an active research fellow program that includes one formal meeting per week and informal training.